An active object that performs its processing through an associated call back function, and which is only performed once. More...

#include <e32base.h>

Inheritance diagram for CAsyncCallBack:

Public Member Functions
IMPORT_C	CAsyncCallBack (TInt aPriority)
	Constructor taking a priority value.

IMPORT_C	CAsyncCallBack (const TCallBack &aCallBack, TInt aPriority)
	Constructor taking a priority value and a callback.

IMPORT_C void	Set (const TCallBack &aCallBack)
	Sets the call back.

IMPORT_C void	CallBack ()
	Queues this active object to be run, if it is not already queued.

virtual IMPORT_C	~CAsyncCallBack ()
	Destructor.

Public Member Functions inherited from CAsyncOneShot
IMPORT_C	CAsyncOneShot (TInt aPriority)
	Constructor taking a priority value.

virtual IMPORT_C void	DoCancel ()
	Implements cancellation of an outstanding request.

virtual IMPORT_C void	Call ()
	Queues this active object to be run once.

virtual IMPORT_C	~CAsyncOneShot ()
	Frees resources prior to destruction.

RThread &	Thread ()
	Gets a handle to the current thread.

Public Member Functions inherited from CActive
IMPORT_C	~CActive ()
	Frees resources prior to destruction.

IMPORT_C void	Cancel ()
	Cancels the wait for completion of an outstanding request.

IMPORT_C void	Deque ()
	Removes the active object from the active scheduler's list of active objects.

IMPORT_C void	SetPriority (TInt aPriority)
	Sets the priority of the active object.

TBool	IsActive () const
	Determines whether the active object has a request outstanding.

TBool	IsAdded () const
	Determines whether the active object has been added to the active scheduler's list of active objects.

TInt	Priority () const
	Gets the priority of the active object.

Public Member Functions inherited from CBase
	CBase ()
	Default constructor.

virtual IMPORT_C	~CBase ()
	Virtual destructor.

TAny *	operator new (TUint aSize, TAny *aBase) __NO_THROW
	Initialises the object to binary zeroes.

TAny *	operator new (TUint aSize) __NO_THROW
	Allocates the object from the heap and then initialises its contents to binary zeroes.

TAny *	operator new (TUint aSize, TLeave)
	Allocates the object from the heap and then initialises its contents to binary zeroes.

TAny *	operator new (TUint aSize, TUint aExtraSize) __NO_THROW
	Allocates the object from the heap and then initialises its contents to binary zeroes.

TAny *	operator new (TUint aSize, TLeave, TUint aExtraSize)
	Allocates the object from the heap and then initialises its contents to binary zeroes.

Protected Member Functions
virtual void	RunL ()
	Handles an active object's request completion event.

Protected Member Functions inherited from CActive
IMPORT_C	CActive (TInt aPriority)
	Constructs the active object with the specified priority.

IMPORT_C void	SetActive ()
	Indicates that the active object has issued a request and that it is now outstanding.

virtual IMPORT_C TInt	RunError (TInt aError)
	Handles a leave occurring in the request completion event handler RunL().

virtual IMPORT_C TInt	Extension_ (TUint aExtensionId, TAny &a0, TAny a1)
	Extension function.

Protected Attributes
TCallBack	iCallBack
	The callback object that encapsulates the callback function.

Additional Inherited Members
Public Types inherited from CActive
enum	TPriority { EPriorityIdle =-100 , EPriorityLow =-20 , EPriorityStandard =0 , EPriorityUserInput =10 , EPriorityHigh =20 }
	Defines standard priorities for active objects. More...

Static Public Member Functions inherited from CBase
static IMPORT_C void	Delete (CBase *aPtr)
	Deletes the specified object.

Public Attributes inherited from CActive
TRequestStatus	iStatus
	The request status associated with an asynchronous request.

Detailed Description

An active object that performs its processing through an associated call back function, and which is only performed once.

API status: Published to all clients. Released API.

Definition at line 1851 of file e32base.h.

Constructor & Destructor Documentation

◆ CAsyncCallBack() [1/2]

IMPORT_C CAsyncCallBack::CAsyncCallBack ( TInt aPriority )

Constructor taking a priority value.

Specifically, the constructor sets this active object's priority value through a call to the base class constructor in its ctor list.

No call back is set, which means that it must be set subsequently through a call to the Set() function.

CAsyncCallBack::Set

Parameters

aPriority The active object priority value. CActive::TPriority defines a standard set of priorities.

(generated from Symbian Developer Library)

◆ CAsyncCallBack() [2/2]

IMPORT_C CAsyncCallBack::CAsyncCallBack	(	const TCallBack &	aCallBack,
		TInt	aPriority
	)

Constructor taking a priority value and a callback.

Specifically, the constructor:

sets this active object's priority value through a call to the base class constructor in its ctor list
sets the callback; the function encapsulated by the callback is called when this active object is scheduled to run.

Parameters

aCallBack	A reference to a callback object encapsulating a function which is called when this active object is ready to run. The constructor takes a copy of this callback object, which means that it can be safely discarded after construction.
aPriority	The active object priority value.

(generated from Symbian Developer Library)

◆ ~CAsyncCallBack()

IMPORT_C CAsyncCallBack::~CAsyncCallBack ( )

virtual

Destructor.

(generated from Symbian Developer Library)

Member Function Documentation

◆ CallBack()

IMPORT_C void CAsyncCallBack::CallBack ( )

Queues this active object to be run, if it is not already queued.

(generated from Symbian Developer Library)

◆ RunL()

virtual void CAsyncCallBack::RunL ( )

protectedvirtual

Handles an active object's request completion event.

A derived class must provide an implementation to handle the completed request. If appropriate, it may issue another request.

The function is called by the active scheduler when a request completion event occurs, i.e. after the active scheduler's WaitForAnyRequest() function completes.

Before calling this active object's RunL() function, the active scheduler has:

decided that this is the highest priority active object with a completed request
marked this active object's request as complete (i.e. the request is no longer outstanding)

RunL() runs under a trap harness in the active scheduler. If it leaves, then the active scheduler calls RunError() to handle the leave.

Note that once the active scheduler's Start() function has been called, all user code is run under one of the program's active object's RunL() or RunError() functions.

See also: CActiveScheduler::Start; CActiveScheduler::Error; CActiveScheduler::WaitForAnyRequest; TRAPD

Implements CActive.

◆ Set()

IMPORT_C void CAsyncCallBack::Set ( const TCallBack & aCallBack )

Sets the call back.

Parameters

aCallBack A reference to a callback object encapsulating a function which is called when this active object is ready to run.

Panic condition: E32USER-CBase 1 if the active object is currently active.

(generated from Symbian Developer Library)

Member Data Documentation

◆ iCallBack

TCallBack CAsyncCallBack::iCallBack

protected

The callback object that encapsulates the callback function.

Definition at line 1875 of file e32base.h.

The documentation for this class was generated from the following files:

Public Member Functions

Protected Member Functions

Protected Attributes

Additional Inherited Members

Detailed Description

Constructor & Destructor Documentation

◆ CAsyncCallBack() [1/2]

◆ CAsyncCallBack() [2/2]

◆ ~CAsyncCallBack()

Member Function Documentation

◆ CallBack()

◆ RunL()

◆ Set()

Member Data Documentation

◆ iCallBack